This invention relates in general to cushions for seating, and, more particularly, to a modular wheelchair cushion having a shaped waterblown foam base.
The foamed base of this application is for use with the modular cushion shown in Ser. No. 07/839,305 now abandoned in favor of continuation-in-part application Ser. No. 08/053,551, and the disclosure of Ser. No. 07/839,305 now abandoned is incorporated herein by reference as if Ser. No. 07/839,305 now abandoned were set forth in its entirety herein. The base is adaptable for use with pads with upstanding air cells such as those shown in Graebe U.S. Pat. No. 4,541,136, preinflated cells as shown in Graebe U.S. Pat. No. 5,152,023 and co-pending Graebe design application Ser. No. 29/000,120 filed Oct. 5, 1992, and any of the variations shown in Ser. No. 07/839,305, now abandoned the hollow dome shaped pads shown in Sias, et al. U.S. Pat. Nos. 4,673,305, 4,605,582 and U.S. Pat. No. Des. 294,212 "T-foam", molded domes, or arch elements as shown in Graebe U.S. Pat. No. 4,713,854.
The base of this invention also can be used with the cover shown in Ser. No. 07/839,305 now abandoned or Graebe U.S. Pat. No. 5,111,544.
The base shown and claimed in Ser. No. 07/839,305 now abandoned is fluorocarbon blown and this created a skin on the molded surfaces which gives the base rigidity and firmness combined with its being light in weight because a low density composition can be used. The skin that forms on the outer surface gives stability even to a lightweight low density product.
However, environmental standards now require that no fluorocarbons be used in making foamed plastic parts. Therefore, water based blowing agents must be used. These generate Co.sub.2 as the blowing agent which is not as harmful to the environment as the fluorocarbons. Unfortunately, CO.sub.2 blown foam does not have an outer skin and therefore is relatively more flexible and less stable than fluorocarbon blown foam of the same density.
It therefore is a primary object of the present invention to provide a waterblown urethane foam cushion base which is relatively light in weight and still has the required rigidity and soft feel to the user.